Sex, age, and training modulate spatial memory in the rhesus monkey (Macaca mulatta)

Area of Science:

• Cognitive Neuroscience
• Primate Behavior
• Aging Research

Background:

• Spatial memory is crucial for survival and navigation.
• Age-related cognitive decline is a significant concern in both humans and animals.
• Sex differences in cognitive abilities and aging patterns are increasingly recognized.

Purpose of the Study:

• To investigate age and sex differences in spatial working and reference memory in rhesus monkeys.
• To examine the effect of prior training on spatial memory performance in different age and sex groups.
• To understand the plasticity of spatial memory in response to training, particularly in young females.

Main Methods:

• 90 rhesus monkeys (Macaca mulatta) were tested on the spatial Delayed Recognition Span Test.
• Performance metrics included accuracy and response latency for working and reference memory components.
• A subset of 22 monkeys received pre-training on a simpler task version before formal testing.

Main Results:

• Spatial memory performance significantly declined with increasing age.
• Male monkeys consistently scored higher than females, indicating a male advantage in spatial memory.
• The rate of age-related decline in spatial memory was more pronounced in males than in females.
• While both working and reference memory declined with age, only working memory exhibited significant sex differences.
• Pre-training had no significant effect on male performance but dramatically improved working memory in young females, reversing initial deficits.

Conclusions:

• Rhesus monkeys exhibit age-related declines in spatial memory, with males showing a more rapid decline than females.
• A young male advantage in spatial working memory was confirmed.
• Prior training can effectively mitigate or reverse spatial working memory deficits in young female monkeys, highlighting cognitive plasticity.